1. Field of the Invention
The present invention relates to a surgical instrument for forming a suture knot in tissue at a surgical site remote from an opening leading to the site.
2. Description of Related Art
In both open and endoscopic surgery, it often is necessary to form a knot at a surgical site remote from an opening leading to the site. Tying an effective knot requires pulling the suture ends in a plane parallel to the surface of the tissue being brought together. The knot tying process requires a first loop to be self-retaining while subsequent loops are formed and moved to the desired knot location.
Securing the knot at the surgical site is dependent upon the nature of the suture material. Rough or compliant material is more likely to stay in place. Also critical in securing the knot is the knot tying technique. Pressure exerted on a single suture end during tying would produce an asymmetrical force tending to disrupt the surgical site. Thus, the optimum technique in forming a knot is to simultaneously pull in parallel both ends of the suture, thereby creating symmetrical pressure on the loop. However, in some types of surgical circumstances, and particularly when using a cannula as is customary in endoscopic surgery, it is not possible to manipulate suture ends in the plane of the tissue and pull them in a plane parallel to the tissue to be joined.
Known suture procedures for forming a knot at a remote surgical site typically involve forming a loop outside the opening to the site, moving the loop down the length of the passage to the site, forming a second loop in the suture outside the opening and moving that loop to the site so that it rests atop the first loop, and thereafter repeating the process, as required, so as to form the desired knot.
Attempts have been made to provide surgical instruments which aid in performing the foregoing procedure to approximate a parallel pull of suture ends in a plane parallel to the tissue to be joined. For example, U.S. Pat. No. 5,087,263 discloses a suture loop holder and run down system having a body with distal and proximal ends. The distal end has a concave shape for receiving loops of suture. However, the loops may loosen as they are delivered to the surgical site, because adequate pressure cannot be exerted on the loops due to the concave shape of the distal end of the holder. Thus, a tight knot may not be formed at the surgical site.